主动脉瓣反流表现为（）
A.二尖瓣城墙样改变
B.二尖瓣SAM现象
C.二尖瓣吊床征
D.二尖瓣舒张期震颤波
E.二尖瓣钻石征
参考答案：D
5克盐放入200克水中，盐与盐水的比是______：______．
用合适的介词填空。
1. The teacher is talking _____ my mother.
2. We walked _____ Chang'an Park yesterday.
3. My mother went to Shanghai yesterday. Now she is arriving home ______ Shanghai.
4. I like dogs. So my father wants to buy dog ______ me.
5. I looked ______ many video shops. At last, I found the CD.
